2.48. Nonmetals http://www.ck12.org
TABLE2.10:(continued)
Illustration Property
Most nonmetals are poor conductors of heat. In fact,
they are such poor conductors of heat that they are often
used for insulation. For example, the down filling in
this sleeping bag is full of air, which consists primarily
of the nonmetal gases oxygen and nitrogen. These
gases prevent body heat from escaping to the cold
outside air.
Solid nonmetals are generally dull and brittle like these
pieces of iodine. Like other nonmetals, iodine lacks the
luster of metals and will easily crack and crumble.Reactivity of Nonmetals
Reactivity is how likely an element is to react chemically with other elements. Some nonmetals are extremely
reactive, whereas others are completely nonreactive. What explains this variation in nonmetals? The answer is
their number of valence electrons. These are the electrons in the outer energy level of an atom that are involved in
interactions with other atoms. Let’s look at two examples of nonmetals, fluorine and neon. Simple atomic models
of these two elements are shown in theFigure2.94.
Q:Which element, fluorine or neon, do you predict is more reactive?
A:Fluorine is more reactive than neon. That’s because it has seven of eight possible electrons in its outer energy
level, whereas neon already has eight electrons in this energy level.
FIGURE 2.94
Although neon has just one more electron than fluorine in its outer energy level, that one electron makes a huge
difference. Fluorine needs one more electron to fill its outer energy level in order to have the most stable arrangement
of electrons. Therefore, fluorine readily accepts an electron from any element that is equally “eager” to give one
up, such as the metal lithium or sodium. As a result, fluorine is highly reactive. In fact, reactions with fluorine are
often explosive, as you can see in the URL below. Neon, on the other hand, already has a full outer energy level. It